Mercuric iodide detector spectrometers are known in the art. Such systems beside the detector include an amplification circuit with a field effect transistor (FET) and a circuit for a pulsed optical or other pulsed charge restoration reset. Such prior art systems also include two Peltier coolers, one for the transistor and one for the detector. Although Mercuric Iodide spectrometers can operate at room temperature, it is possible to obtain a lower electronic noise and a higher energy resolution when the detector and the FET are cooled. In addition, the cooling of both components to the predetermined temperature allows the construction of systems with parameters stable over the wide range of ambient temperatures. The necessity for two coolers arises from the fact that the transistor and the detector have to be maintained at different temperatures, the FET requiring a significantly lower temperature to avoid the unwanted leakage current which occur through the gate of the transistor.
Pulsed optical or other pulsed charge restoration feedback amplification systems require higher detector leakage currents than the FET leakage currents. This requirement forces operation of the detector at temperatures much higher than optimum.
The use of two coolers results in relatively high power requirements and relatively large size for the system.